Iron: Essential component in the formation of hemoglobin; adequate amounts of iron are necessary for effective erythropoiesis; also serves as a cofactor of several essential enzymes, including cytochromes that are involved in electron transport. Replacement of iron stores found in hemoglobin, myoglobin, and enzymes; works to transport oxygen via hemoglobin. Folic acid: Required for nucleoprotein synthesis and the maintenance of normal erythropoiesis; folic acid is converted in the liver and plasma to its metabolically active form, tetrahydrofolic acid, by dihydrofolate reductase; prevents neural tube defects in women of childbearing potential and higher doses required during pregnancy.